HEELING EXPERIMENT

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heights of the centre of gravity and of metacentre above the Keel,
provide information which offers a starting off point from whidh the
G M for various conditions of loading may be computed.

THE HEELING EXPERIMENT TO FIND G M.

The displacement of the ship is carefully calculated by the builders
by adding up the weights of all the materials in her construction and
of stores, equipment and any ballast or cargo that may be on board
at the time. Let us assume a displacement of 2000 tons; the ship
should be upright, loosely moored by the head and stern, absolutely
free to incline and the weather should be calm

(i) A known weight, say 10 tons, is placed exactly in the middle
line of the vessel (56-lb. weights are convenient to handle and are
uniform in shape). A cord is fixed to a hatch coaming with a plumb
bob attached to its lower end reaching down into a hold and free to
pendulate across the face of a batten fixed athwartship and divided
into fractions of an inch. The initial position of the cord P Q on the
scale is carefully noted.

(ii) The 10-ton weight is then shifted from the middle line to one
side of the ship and the exact distance the centre of the weight has been
moved transversely is accurately measured, say 20 feet. This gives a
"shift" moment of 10 tons X20 feet=200 foot-tons, or, in general terms.
«?xd=shift moment, where w is the weight and d the distance it has
been moved athwartships.
The distance, R Q in Figure 30, through which the plumb line fcas